The Wife is narrating her own experience, a fact she makes clear right at the start of her Prologue. As a narrator, the Wife seems candid and honest, freely admitting things a more inhibited person would hide, like her intention of engaging in sex as frequently as possible. Yet the Wife also owns up to being deceptive with her former husbands and claims that deceit is one of the God-given gifts of women. This admission complicates our ability to trust the Wife as a narrator. What's to prevent her from lying to us, too? Rather than trying to figure out what's true and what's not in what the Wife says, we're better served by trying to figure out what her statements indicate about her motivations. In other words, what is the Wife trying to do or gain by saying this or that?
While most of the Wife's Prologue is in first person, a substantial portion of it, from lines 241-384 and 437-456, are the Wife's re-enactment of how she spoke to her husbands, making it one of the rare narratives in literature in the second person. The Wife addresses her husband as "ye" and "thou" in this portion, as in "Thow seyst that dropping houses and eek smoke / And chyding wyves maken men to flee" (284-285). And that sentence pretty much sums up the content of the second person narration part of the Prologue: the Wife chides her husband by accusing him of saying horrible things about wives.
It's important to remember that the Wife doesn't have to re-enact her scolding. Instead, she could narrate it in the third person, as in, "Then I told my husband that he had said such and such." But by re-enacting it so that it's in second person, before a mostly male audience, the Wife's rant seems like it's addressed to them, and to us. The Wife's audience becomes implicated in the same antifeminist rhetoric of which the Wife accuses her husband, which, in a Prologue partially concerned with showcasing the ugliness of this rhetoric, is an effective strategic move.